Optical discs have been used for detection and characterization of biological and chemical samples. For instance, see WO 96/09548 (Gordon), EP A 392475 (Idemitsu), EP A 417 305 (Idemitsu), EP A 504432 (Idemitsu), and WO 98/12559 (Demers), all of which are incorporated herein by reference. Other examples of using optical discs to detect investigational samples can be found in U.S. Provisional Application 60/252,725, entitled “Optical Bio-Disc Including Microfluidic Circuit For Separation And Quantification Of Agglutinated Microparticles Or Cells And Methods Relating Thereto,” U.S. Provisional Application No. 60/252,726, entitled “Bioactive Solid Phase For Specific Cell Capture And Optical Bio-Disc Including Same,” and U.S. Provisional Application No. 60/257,705, entitled “Surface Assembly For Immobilizing DNA Capture Probes And Bead-Based Assay Including Optical Bio-Discs And Methods Relating Thereto,” all of which are incorporated herein by reference.
These previously described optical discs, however, are not designed to be read by standard optical disc readers, such as standard CD or DVD readers. For instance, the optical discs disclosed in EP A 392475 (Idemitsu), EP A 417 305 (Idemitsu) and EP A 504432 (Idemitsu) require the use of two optical detectors, one to detect the tracking information and the other to detect surface structures. In contrast, reading a standard CD or DVD needs only one optical detector.
Therefore, there is a need to design and manufacture an optical disc configured to receive an investigational sample which can be detected by a standard optical disc reader or an optical disc reader modified therefrom.
Over the past decade, scanning laser microscopy (SLM) has revolutionized life science imaging. However, SLM demands expensive and specialized optical equipment. Consequently, there exists a need to provide an inexpensive, generic device which can carry out laser scanning over microscopic specimens.
The present invention discovers that the minimum mechanical requirements for SLM, i.e. laser, focusing and detection optics, precision scanning means, and computer interface, may all be provided by a standard optical disc reader or an optical disc reader modified therefrom. Therefore, it is desirable to create an optical disc which can hold a microscopic sample that can be scanned by a standard optical disc reader. Such an optical disc presents a marked advantage over existing SLM technologies.
In order for a standard optical disc reader to operate an optical disc, the optical disc reader is typically required to be able to (1) accurately focus above the operational surface of the optical disc, (2) accurately follow the spiral track or utilize some form of uniform radial movement across the optical disc surface, (3) recover enough information to facilitate a form of speed control, such as CAV, CLV, VBR, CBR, or ZCLV, (4) maintain proper power control by logical information gathered from the optical disc or by signal patterns detected in the operational surface of the optical disc, and (5) respond to logic information that is used to control, for example, the position of the objective assembly, the speed of rotation or the focusing position of the laser beam.
A typical optical disc system uses elements of the optical medium itself to satisfy at least some of these operational requirements. For instance, in a typical CD, the disc substrate is impressed with a spiral track made up of a series of embossed or impressed pits and lands. Light reflected from these pits and lands can be used to generate signals. These signals are used by the optical disc reader to maintain proper focusing and tracking. In a CD-R disc, a wobble groove is used to generate operational signals during disc recording. Dye marks are created during disc recording, and these dye marks may provide the requisite tracking structures during subsequent reading. Generally, under each of conventional optical disc standards, the structures that encode data may simultaneously serve to provide operational signals that enable an optical disc reader to operate the optical disc.
Conventional optical disc standards make no provision with respect to acquisition of information from investigational features, such as biological or chemical specimens, that are disposed on the disc. Investigational features disposed on the disc may disrupt the tracking of the disc. In addition, investigational features may be sufficiently separated from operational structures, therefore preventing an optical disc reader from tracking the disc and detecting the investigational features concurrently and discriminably.
Therefore, there is a need to provide an optical disc which allows an optical disc reader to detect the investigational features without disrupting the tracking of the disc. There also exists a need to provide an optical disc which allows an optical disc reader to track the disc and read the investigational features concurrently and discriminably.